This invention relates generally to sonar systems and more particularly to sonar systems adapted to aid in the detection and avoidance of sea bottom hazards which could damage a sea going vessel's hull.
As is known in the art, charted depth data is used as a primary navigation aid in avoiding reef and other sea bottom hazards. Sometimes this charted depth information changes over time because earth disturbances may create new, previously uncharted hazards. Thus, current underwater hazard avoidance techniques are supplemented with on-board sonar mapping of the sea's bottom. Current sonar imaging provides high resolution of the sea bottom profile when using a vertical, or substantially vertical, depth measurement. However, with the advent of large ocean-going vessels, particularly the new massive oil tankers, early warning of forward navigational hazards is required because of the relatively long intervals of time which are required either to slow down or to change course.